Radio frequency identification (RFID) systems use radio frequency electromagnetic waves to communicate between tags and an interrogator/reader. The tag may store or represent information about an object to which the tag is attached. Such information may include a unique identifying number, object status, location, and the like. Unlike bar codes and other systems that use optical technology, RFID tags do not have to be in the direct line of sight of the interrogator/reader but need only be located within its EM field. The tag may be attached to an individual item or to packaging containing multiple items. When the item or packaging is passed through the electromagnetic field of the reader/interrogator, signals from the attached tag are sent to the reader to identify or present information associated with the object. RFID systems may be passive or active; in passive systems, the RFID tags obtain operating power generated from the interrogator/reader while in active systems, the tags are powered by a battery located on the tag.
The cost of RFID tags is a major obstacle in expanding the use of RFID for object tracking. Conventional RFID systems store information in a simple integrated circuit on the tag. The systems require an antenna, generally copper, on the tag to send and receive signals. Antenna material and manufacturing costs are a large component of the overall cost of a tag. Antennas also present manufacturing and durability concerns. In addition, conventional RFID tags present security concerns as they are subject to reprogramming.
It would be desirable to have easier and cheaper methods of producing RFID tags. It also would be desirable to have RFID tags and systems that do not require tag antennas. Such tags would be more durable (i.e. with no points of attachment) and reduce manufacturing and design difficulties. It would further be desirable to have RFID tags that are not susceptible to reprogramming.